Member Since: 03 Mar 2019
Location: Tasmania
Posts: 184
D4 and LED trailer lights - how many resistors are required?
I’ve been reading a number of older discussion threads about using LED trailer lights with the Discovery 4 and the need for load resistors so that the D4 can sense that a trailer is hitched. However the requirements for resolving this seem to differ significantly, so far I’ve read all of the following:
Both resistors and relays are required - seems to be outdated for the D4 and be what the earlier D3’s needed rather.
Only one resistor is required on either of the indicator circuits - but the trailer light on the dash will only flash for one sides indicator then though.
Two resistors are required - one for each indicator circuit.
Three resistors are required - one for each indicator circuit and one for the taillight circuit as apparently the vehicle rechecks for the trailer each time the door is opened.
Is anyone able to please confirm for me what is correct for resolving the issue?Mine - MY09 L319 D3 HSE Lion 2.7 TDV6 and modified MY03 LT L318 Discovery 2a HSE Td5 15P
Hers - MY12 L319 D4 Lion 2.7L TDV6
Dads - MY12 L319 D4 Lion 2.7L TDV6
20th Feb 2020 6:16 am
stew 46
Member Since: 01 Dec 2011
Location: cornwall
Posts: 10148
Try one of these
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if you cant hold on dont let go , it ill come in handy for something even if you never use it.
D3 SE 05,
110 s wagon 300 tdi SOLD
h top transit
crew cab transit
transit connect
ausa dumper, muck truck .
peljob 2.5 digger
06 L 200 crew cab
20th Feb 2020 6:20 am
Jetlag
Member Since: 10 Mar 2012
Location: Johannesburg
Posts: 205
Well, the first problem is 99% of people dont know how to correctly install the load resistors so i hope this will help you. I have fitted a resistor on each indicator light and the LR immediately picked up the trailer
For the Disco 3 or 4 the resistors need to be 10ohm 15Watt... 1 on each indicator and the problem is solved
See diagram below
Click image to enlarge
Disco 4 SDV6 HSE with Compomotives, BFG 265/65R18s, BigCountry drawer system, Melvill & Moon covers, NL 52L fridge, FR Spare Wheel Carrier, FR Roof Rack, Tenco RTT, FR 50" LED Bar, dual spots, Lift Rods, Mantec Snorkel, C-TEK Dual batt system, 270 Ostrichwing, Maxtrax, Icom ID-5100, Icom ID-51 as secondary, IIDtool BT
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28th Feb 2020 7:11 am
Kelvo
Member Since: 07 Aug 2015
Location: Perth WA
Posts: 264
Re: D4 and LED trailer lights - how many resistors are required?
twr7cx wrote:
I’ve been reading a number of older discussion threads about using LED trailer lights with the Discovery 4 and the need for load resistors so that the D4 can sense that a trailer is hitched. However the requirements for resolving this seem to differ significantly, so far I’ve read all of the following:
Both resistors and relays are required - seems to be outdated for the D4 and be what the earlier D3’s needed rather. Resistors and relays only for D3.
Only one resistor is required on either of the indicator circuits - but the trailer light on the dash will only flash for one sides indicator then though. This is correct.
Two resistors are required - one for each indicator circuit. This is correct.
Three resistors are required - one for each indicator circuit and one for the taillight circuit as apparently the vehicle rechecks for the trailer each time the door is opened. This is NOT correct.
Is anyone able to please confirm for me what is correct for resolving the issue?
I spliced into the left and right indicator tow socket wiring in the left hand boot compartment. These two cables connect to one pole each of the switch. I mounted the switch so it is tucked on the sloping underside near the 12v outlet on the left side in the boot. Then two cables from the switch to the resistors, the resistors are then connected to the body ground point. I mounted the resistors to an aluminium heatsink that I already had, then mounted the heatsink to the back of the towhitch bracket in the left side storage area. The photo shows the heatsink in place, but with the polystyrene hitch holder not fitted yet. The resistors are tucked away on the back so are physically protected.
MY14 TDV6
28th Feb 2020 11:55 pm
jonnyboy54321
Member Since: 14 Jul 2012
Location: surrey
Posts: 121
stew 46 wrote:
Try one of these
Does anyone know if these definitively work on a d4 for the issues mentioned ie not disabling parking sensors when towing? I hire/borrow two or three different ones so adding a resistor/relay to the towed item isn't an option.
7th Jan 2022 8:57 am
Trailered Movements
Member Since: 16 Jan 2020
Location: East/West Sussex Coast Borders
Posts: 1200
I fitted 2 resistors, and have a switch close by that operates on the earth wire(s). That way I can use a trailer with LEDS or bulbs with a simple flick of a switch without any issues.
Dave2011 Discovery 4 Commercial SDV6 (Gone)
2010 RRS TDV8 (Gone)
1980 OBLIC 4.0ltr Range Rover (went a long time ago)
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